500 mAh is a capacity, not a charge rate. The charge rate is in mA. I think a "1C" rate is the current it would take to reach capacity in 1 hour. In your case: 500 mA (0.5 A).

The schematic shows that the charge current is 1000/R and the built-in R is 10K. This makes the default current 100 mA (0.1A). The schematic also says that to get the maximum allowable charge current add a 2.5K resistor. In the product description it says that the maximum allowed charge current is 500 mA (0.5 A).